(1) Field of the Invention
The present invention relates to sea state measuring systems or devices, and relates more specifically to the deployment of a subsurface buoy, the position of the buoy is carefully controlled relative to the sea surface in order to provide information with respect to the surface sea state from locations below the sea surface, such as a submerged platform or submarine.
(2) Description of the Prior Art
A submerged vessel will have little knowledge of sea state, and historically must surface in order to provide the crew with a subjective qualitative picture of sea state. The more sophisticated methods currently in use rely on measurements of acoustic noise generated by sea surface waves and received by passive transducers contained on or near the submarine. Both these prior art approaches to the analysis of sea state lack the quantitative approach needed and achieved by subject invention.
The need for measuring surface conditions, particularly wave conditions, from a submerged submarine can be traced to the profound effect that the surface condition will have not only on a decision to launch submarine missiles, but also upon the potentially destabilizing effect of higher order sea states on the launching submarine itself.
Various methods for measuring ocean surface conditions such as wave heights and the like are currently available. However, such sensing methods include the need for tethered instrumented buoys such as accelerometer equipped buoys. The latter approach is demonstrated in Miller U.S. Pat. No. 4,794,575 wherein a submarine launched self-contained sea state buoy is disclosed. The buoy is adapted to float at the sea surface and transmits sea state data over a data link carried by the buoy tethering cable. Tethered buoys such as shown in the Miller patent limit submarine operating capabilities by placing restrictions on permissible submarine speed and depth for the period during which the buoy is deployed. In addition, the buoy can be detected by hostile forces more easily than with the system of the present invention.
Another prior art reference; U.S. Pat. No. 3,534,599 issued to Hoehne discloses an expendable ocean wave meter provided on a tethered floating buoy. Although a pressure sensing device is provided below the surface of the water the buoy is exposed at the surface and therefore this device suffers from the same disadvantages as referred to previously with reference to the Miller patent.
Middleton et al; U.S. Pat. No. 4,135,394 discloses, a wave amplitude measuring buoy. Here again the buoy must be provided at the surface of the water, and a single axis accelerometer provided a fixed distance below the water surface to monitor wave action. Furthermore, the output of the accelerometer must be stabilized to provide an output proportional only to the vertical acceleration of the buoy. The device and system of the present invention not only avoids the need for floating buoys at the sea surface, but also avoids many of the needs for accepting the inherent inaccuracies of these prior art systems and devices.